For years, the U.S. government has warned travelers they will soon need a Real ID to board domestic flights, only to keep postponing the deadline. But “soon” appears to be real this time.

As of May 7, a standard driver’s license or state ID will no longer pass muster at airport security checkpoints, the Department of Homeland Security says. Passengers will instead need to present a security-enhanced, star-emblazoned Real ID or another approved form of identification like a passport.

The change, nearly 20 years in the making, is meant to enhance security by setting a more consistent standard for state-issued documentation, according to the Department of Homeland Security.

Here’s what you need to know about the coming deadline.

What is a Real ID?

A Real ID is a federally compliant state-issued driver’s license, learner’s permit or nondriver ID. Real IDs are marked with a star — generally gold or black — and vary in appearance by state or territory.

Any resident of a U.S. state or territory who wishes to use a driver’s license or nondriver ID at a T.S.A. checkpoint must make sure that it is Real ID-compliant. Driver’s licenses that do not have the star are not Real IDs. Some noncompliant IDs will also have the words “Federal limits apply.”

The percentage of Americans who have updated their driver’s licenses to be Real ID compliant appears to vary widely by state. For example, in Pennsylvania, where there have been reports of long lines at license offices, it is a little more than 26 percent, the state’s Transportation Department said. In California, it is just over 55 percent.